1. Field of the Invention
The present invention relates to a push button type tuner usable for a radio receiver and more particularly to an improved push button type tuner which assures that an operator can selectively tune to one of two preset radio frequencies merely by actuating a single push button.
2. Description of the Prior Art
A widely known conventional push button type tuner is constructed such that a preset radio frequency is allocated to each of a plurality of push buttons, and an operator tunes to a required radio frequency by actuating a corresponding push button. In the conventional push button type tuner as constructed in the above-described manner, only one radio channel can be usually selected by one push button. Thus, to select one of many predetermined radio channels there is necessity for arranging an increased number of push buttons corresponding to the number of radio channels. This causes a tuner to be designed and constructed in larger dimensions. Therefore, when a smaller tuner is employed, it is unavoidably inhibitive to handle a lot of channels therewith.
In view of the drawback of the conventional tuner as mentioned above, there was made a proposal as to a tuner of the above-mentioned type as disclosed in Japanese Utility Model Publication No. 57-43391 which was filed by the same assignee as that of the present invention. The proposed tuner is constructed such that a pair of channel selecting members are disposed with a push button being located at the middle therebetween whereby one of two different radio channels can be selected by actuating the push button so that an operator can pre-set a number of radio channels corresponds to two times the number of push buttons. Specifically, the conventional tuner includes a plurality of channel selecting mechanisms each of which includes a push button, a pair of channel selecting members disposed by both the sides of the push button and a shifting member for selectively inhibiting the one channel selecting member from being displaced by manual operation. Channel shifting is achieved, for instance, to AM band or FM band in dependence on the position determined by the shifting member and thereby an operator can tune to one of two different frequency bands by operating one of the pair of channel selecting shafts disposed by both the sides of the push button. However, the conventional tuner requires that an operator handle the shifting member at every time when he selects either of AM and FM bands. Further, in the case when channel selection is performed for 10 channels by operating 5 push buttons, he achieves channel selection only for a combination of 5 AM bands. Accordingly, he cannot do so for other combination, for instance, of 6 AM bands and 4 FM bands.